scholarly journals Quality control of adjustment of clearances of ball bearing supports, dynamic devices rotor-type, according to parameters of acoustic emission signals

2021 ◽  
Vol 2131 (4) ◽  
pp. 042099
Author(s):  
Ye Lebedev ◽  
I Golikov ◽  
A Repin ◽  
L Bogatov

Abstract The article is devoted to increasing the bearing life of dynamic rotary-type machines by controlling the uniformity of the distribution of the value of the preliminary axial load acting on the rolling bearings of the rotation axis of the power unit. The possibility of monitoring the axial load using acoustic emission (AE) signals is considered. The results of experimental studies of the kinematics of the ball movement relative to other bearing parts, depending on the tightening torque of bolted joints, estimated by the parameters of AE signals, are presented.

2020 ◽  
pp. 26-34
Author(s):  
V. V. Nosov ◽  
I. A. Pavlenko ◽  
A. P. Artyushchenko ◽  
E. V. Grigoriev

Traditionally, the problem of monitoring the condition of rolling bearings can be solved based on registration of control signals that occur when the bearing performs a kinematic function due to contact of surface damage which is accumulated and caused by the processes of friction, impact, heat generation, contact electrical interaction, generation of elastic vibrations from them, etc. Relative to the bearing function of bearings, the diagnostic value of such signals is quite low, since they depend on many factors that are not related to resource-determining processes and play a destabilizing role in establishing the connection between control parameters and condition. The solution of the problem must be carried out based on a systematic approach linking the control of the object with the main criterion of its performance. Since the cause of bearing failures is fatigue processes occurring in the material of their elements, the most promising methods are those based on the registration of signals associated with the restructuring of the structure and the accumulation of damage of the material, and in particular, the method of acoustic emission (AE) based on recording the phenomenon of waves of elastic radiation at loading. The development of the acoustic emission method for monitoring the state of rolling bearings is based on a multi-level model of the time dependence of AE parameters, and the control is based on the assessment of the intensity parameters of the resource-determining stage of uniform elastic fracture of representative structural elements of the material of the test object. AE informative signals are selected, and diagnostic parameters are determined at the interlevel transition from macro- to micro- and nano-level. The idea of the transitions is to select representative informative parameters and to trace the connection between them through AE strength indicators that can highlight a useful signal in conditions of high instability and heterogeneity of the accompanying processes. The experimental stup and the results of experimental studies of AE of rolling bearings with an artificially created defect on the surface of the outer ring are described, the results of control are compared with the results of the analysis of the stress-strain state around the created defect, the informative value of the concentration and kinetic index and the possibility of evaluating the resource based on it are shown.


Lubricants ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 37 ◽  
Author(s):  
Alan Hase

As rolling bearings are widely used in various machines, there is a strong need to detect any problems as early as possible. Although vibration analysis is commonly used in the diagnosis of rolling bearings, it is possible that the failure of such bearings might be detected earlier by an acoustic emission (AE) technique. Methods for detecting potential fatigue damage in a thrust ball bearing by AE signal analysis and by vibration analysis were compared. For the AE signal analysis, the maximum amplitude and the frequency spectrum were used to detect and identify fatigue damage in the bearing. Features of AE signals detected when a defect was artificially formed on the raceway surface of a bearing by using a Vickers hardness tester were also examined. The AE technique detected initial cracks due to fatigue damage earlier than the vibration technique. Additionally, AE signals were always detected during bearing fatigue tests, but the AE signals detected during the running-in process, crack initiation, crack propagation, and flaking all contained different frequency components. Furthermore, the correlation map between the frequency spectra of AE signals and deformation and fracture phenomena (friction and wear modes) was updated by adding the new findings of this study.


2019 ◽  
Vol 945 ◽  
pp. 515-521 ◽  
Author(s):  
O.V. Bashkov ◽  
A.A. Bryansky ◽  
I.V. Belova ◽  
Denis B. Solovev

This paper presents the results of the study of strength and fracture processes of FRP samples, obtained by vacuum and vacuum-autoclave molding methods. The experimental studies consisted of a three-point bending test with step loading, accompanied by an acoustic emission method. Based on the acoustic emission data recorded using the acoustic-emission software and hardware complex during the experiments, a method for estimating the accumulated damage using various techniques for analyzing acoustic emission parameters was tested. The results of methods for analyzing the power-law coefficient of accumulation of total AE, b-value and density distribution of amplitudes and median frequencies are considered. An estimate of the power-law coefficient of accumulation of the total AE made it possible to determine the bearing capacity of PCM samples. Using the techniques for analyzing the amplitude distribution of the AE signals and the distribution density of the amplitudes and median frequencies of the AE signals, destructive processes in the volume of samples were described and the stages of their damaging were revealed.


2014 ◽  
Vol 494-495 ◽  
pp. 1513-1516
Author(s):  
Man Cheng Yi ◽  
Jian Fang ◽  
Yong Wang ◽  
Zhi Ning Li ◽  
Chun Hui Gu ◽  
...  

Experimental studies have shown that Acoustic Emission (AE) signals generated by the polluted-insulator discharge contain information of discharge energy. To extract the frequency characteristics of AE signals in polluted-insulator discharge, algorithm combining the empirical mode decomposition (EMD) and fast fourier transform (FFT) is used. Through a great many of artificial contamination experiments, the AE signals in different contamination discharge stages are collected, and the frequency characteristics can be extracted by the method presented in this article. The results show that the frequency characteristics of AE signals can be effectively extracted by the proposed method, which gives the right corresponding relationship between frequency characteristics and the polluted-insulator corona, partial and arc discharge. It also provides technical support for monitoring the intensity of polluted-insulator discharge and the change of external insulation status. The method for extracting AE signal frequency characteristics proposed in this paper has been applied to on-line monitoring of polluted-insulator external insulation status and good results have been achieved.


2020 ◽  
pp. 43-50
Author(s):  
A.S. Komshin ◽  
K.G. Potapov ◽  
V.I. Pronyakin ◽  
A.B. Syritskii

The paper presents an alternative approach to metrological support and assessment of the technical condition of rolling bearings in operation. The analysis of existing approaches, including methods of vibration diagnostics, envelope analysis, wavelet analysis, etc. Considers the possibility of applying a phase-chronometric method for support on the basis of neurodiagnostics bearing life cycle on the basis of the unified format of measurement information. The possibility of diagnosing a rolling bearing when analyzing measurement information from the shaft and separator was evaluated.


2021 ◽  
Vol 11 (15) ◽  
pp. 7045
Author(s):  
Ming-Chyuan Lu ◽  
Shean-Juinn Chiou ◽  
Bo-Si Kuo ◽  
Ming-Zong Chen

In this study, the correlation between welding quality and features of acoustic emission (AE) signals collected during laser microwelding of stainless-steel sheets was analyzed. The performance of selected AE features for detecting low joint bonding strength was tested using a developed monitoring system. To obtain the AE signal for analysis and develop the monitoring system, lap welding experiments were conducted on a laser microwelding platform with an attached AE sensor. A gap between the two layers of stainless-steel sheets was simulated using clamp force, a pressing bar, and a thin piece of paper. After the collection of raw signals from the AE sensor, the correlations of welding quality with the time and frequency domain features of the AE signals were analyzed by segmenting the signals into ten 1 ms intervals. After selection of appropriate AE signal features based on a scatter index, a hidden Markov model (HMM) classifier was employed to evaluate the performance of the selected features. Three AE signal features, namely the root mean square (RMS) of the AE signal, gradient of the first 1 ms of AE signals, and 300 kHz frequency feature, were closely related to the quality variation caused by the gap between the two layers of stainless-steel sheets. Classification accuracy of 100% was obtained using the HMM classifier with the gradient of the signal from the first 1 ms interval and with the combination of the 300 kHz frequency domain signal and the RMS of the signal from the first 1 ms interval.


2021 ◽  
Vol 11 (14) ◽  
pp. 6550
Author(s):  
Doyun Jung ◽  
Wonjin Na

The failure behavior of composites under ultraviolet (UV) irradiation was investigated by acoustic emission (AE) testing and Ib-value analysis. AE signals were acquired from woven glass fiber/epoxy specimens tested under tensile load. Cracks initiated earlier in UV-irradiated specimens, with a higher crack growth rate in comparison to the pristine specimen. In the UV-degraded specimen, a serrated fracture surface appeared due to surface hardening and damaged interfaces. All specimens displayed a linearly decreasing trend in Ib-values with an increasing irradiation time, reaching the same value at final failure even when the starting values were different.


2006 ◽  
Vol 13-14 ◽  
pp. 351-356 ◽  
Author(s):  
Andreas J. Brunner ◽  
Michel Barbezat

In order to explore potential applications for Active Fiber Composite (AFC) elements made from piezoelectric fibers for structural integrity monitoring, a model experiment for leak testing on pipe segments has been designed. A pipe segment made of aluminum with a diameter of 60 mm has been operated with gaseous (compressed air) and liquid media (water) for a range of operating pressures (between about 5 and 8 bar). Artificial leaks of various sizes (diameter) have been introduced. In the preliminary experiments presented here, commercial Acoustic Emission (AE) sensors have been used instead of the AFC elements. AE sensors mounted on waveguides in three different locations have monitored the flow of the media with and without leaks. AE signals and AE waveforms have been recorded and analysed for media flow with pressures ranging from about 5 to about 8 bar. The experiments to date show distinct differences in the FFT spectra depending on whether a leak is present or not.


Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1206 ◽  
Author(s):  
Wei-Jiun Su ◽  
Jia-Han Lin ◽  
Wei-Chang Li

This paper investigates a piezoelectric energy harvester that consists of a piezoelectric cantilever and a tip mass for horizontal rotational motion. Rotational motion results in centrifugal force, which causes the axial load on the beam and alters the resonant frequency of the system. The piezoelectric energy harvester is installed on a rotational hub in three orientations—inward, outward, and tilted configurations—to examine their influence on the performance of the harvester. The theoretical model of the piezoelectric energy harvester is developed to explain the dynamics of the system and experiments are conducted to validate the model. Theoretical and experimental studies are presented with various tilt angles and distances between the harvester and the rotating center. The results show that the installation distance and the tilt angle can be used to adjust the resonant frequency of the system to match the excitation frequency.


2008 ◽  
Vol 13-14 ◽  
pp. 41-47 ◽  
Author(s):  
Rhys Pullin ◽  
Mark J. Eaton ◽  
James J. Hensman ◽  
Karen M. Holford ◽  
Keith Worden ◽  
...  

This work forms part of a larger investigation into fracture detection using acoustic emission (AE) during landing gear airworthiness testing. It focuses on the use of principal component analysis (PCA) to differentiate between fracture signals and high levels of background noise. An artificial acoustic emission (AE) fracture source was developed and additionally five sources were used to generate differing AE signals. Signals were recorded from all six artificial sources in a real landing gear component subject to no load. Further to this, artificial fracture signals were recorded in the same component under airworthiness test load conditions. Principal component analysis (PCA) was used to automatically differentiate between AE signals from different source types. Furthermore, successful separation of artificial fracture signals from a very high level of background noise was achieved. The presence of a load was observed to affect the ultrasonic propagation of AE signals.


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